In a manufacturing facility or inspection facility for semiconductors and liquid crystals, a substrate inspection device is used.
A substrate inspection device is a device for inspecting a substrate. For example, a substrate may be a semiconductor wafer or a liquid crystal substrate. A semiconductor wafer is a wafer such as silicon, gallium, silicon carbide etc.
A substrate inspection device is required to position a substrate. Normally, in order to prevent contamination of a substrate, a simple and reliable positioning mechanism is required.
Also, some substrate inspection devices are used in order to accurately measure amounts of impurities, such as sodium, gallium, or iron, in a film such as an oxide film or nitride film formed on a surface of a semiconductor wafer. With these substrate inspection devices, accurate positioning of a substrate is important for accurate measurement of the impurity amount.
If impurities are contained within a thin film, such as an oxide film or nitride film formed on the surface of a semiconductor substrate, even if the amount of that impurity is microscopic, there will be a significant influence on the electrical characteristics of a semiconductor element.
There has, therefore, been a demand to suppress contamination of impurities from the wafer surface as much as possible in a semiconductor element manufacturing facility.
In order to do this, amounts of impurities existing on the surface of a semiconductor wafer must be accurately measured.
In recent years, amounts of impurities have been measured by holding the impurities in a fluoride solution, instead of using secondary ion mass spectrometry, Auger spectroscopic analysis, or neutron activation analysis to measure amount of impurities existing on a wafer surface. One example of a fluoride solution is HF (hydrogen fluoride) solution.
After dissolving an oxide film on the surface of a silicon wafer in an HF solution, the HF solution is collected, and analysis of impurities within the HF solution is carried out. If the amount of collected HF solution is small, impurity concentration becomes high, which improves measurement precision.
For example, after a substrate is exposed to vapor of HF solution and an oxide film of the substrate is dissolved, a droplet of HF solution on the surface of the substrate is distilled, and this droplet is moved while still attached to the surface of the substrate. Impurities within the oxide film are collected in the droplet. By measuring the amount of impurities inside the droplet, the amount of impurities on the substrate surface is examined.
Since the measurement precision is improved, a substrate inspection device that is capable of measuring amounts of impurities in only a designated region and performing accurate positioning is required. In particular, a substrate inspection device, substrate inspection method and recovery tool suitable for moving a droplet while still attached to a surface of a substrate, and collecting impurities in the droplet are required.
One or more embodiments of the present invention provide a substrate inspection device and substrate inspection method that can improve measurement precision, and a substrate inspection device, substrate inspection method, and recovery tool suitable for causing a droplet to adhere to an outer surface of a substrate and move along the outer surface.